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Finding the Fourth Proportional to 305.20, 420.48 and 231.40

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Solution

The fourth proportional to 305.20, 420.48 and 231.40 is: 318.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.20 : 420.48 = 231.40 : x
  2. Step 2: Convert to fraction form
    305.20/420.48 = 231.40/x
  3. Step 3: Cross multiply
    305.20x = 420.48 × 231.40
  4. Step 4: Simplify right side
    305.20x = 97,299.07
  5. Step 5: Solve for x
    x = 97,299.07/305.20
  6. Step 6: Final answer
    x = 318.80

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.